The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Speakers are used in many systems and devices. For example, speakers are used in systems in concert halls, home theaters, automobiles, and so on. Speakers are also used in devices such as smartphones, laptop computers, and so on. In these systems and devices, audio signals including music and speech are typically amplified, and the amplified signals are input to the speakers.